Video cameras, digital still cameras, etc. utilize semiconductor imaging devices (imaging devices) configured of image sensors such as CCD (Charge Coupled Device), CMOS (Complementary Metal-Oxide Semiconductor), etc. In these imaging devices, each element is provided with a light receiving section including a photodiode. In the light receiving section, entering light is photoelectrically converted to generate signal charges.
In recent years, there has been developed a system (an imaging surface phase difference detection system) in which some of imaging pixels in the imaging device are used for phase detection so as to increase an automatic focusing (AF) speed. The phase difference detection system involves focus detection of a pupil division system with use of a two-dimensional sensor in which each pixel of an image sensor is provided with an on-chip lens.
In such an imaging device, some reports have been made on techniques to attain light receiving characteristics expected in pixels for imaging (imaging pixels) and in pixels for focus detection (imaging surface phase difference pixels). For example, an imaging device is disclosed in which curvatures of on-chip lenses are varied, or a placement surface of the on-chip lens is allowed to be at a different level, pixel by pixel, in a direction of an optical axis, so as to adjust a condensing point of entering light (for example, refer to Patent Literatures 1 and 2). Also, an imaging device is disclosed in which an element isolation layer made of a non-transparent conductive material is provided on a rear surface side of a silicon substrate on a light entering side, allowing for improvement in both pupil division performance and sensitivity (for example, refer to Patent Literature 3). Furthermore, an imaging device is disclosed in which one on-chip lens is assigned to a plurality of imaging surface phase difference pixels whose light receiving surfaces are allowed to be at a different level (for example, refer to Patent Literature 4).